It is important to perform a timing control of a power switchgear when supplying a current to a transformer so as to suppress a transient magnetizing inrush current in the transformer. For example, Patent Literature 1 mentioned below discloses the following technique. Residual magnetic fluxes in respective phases of a three-phase transformer are detected, and an alternating-current (AC) voltage in a reference phase is applied at a timing when a stationary magnetic flux and the residual magnetic flux in the reference phase match each other. Thereafter, AC voltages in the two remaining phases are applied at a timing when the AC voltage in the reference phase becomes zero, thereby suppressing a magnetizing inrush current.